B cells express a wide array of cell surface molecules during their differentiation and proliferation. Examples include the CD10, CD19, CD20, CD21, CD22, CD23, CD24, CD37, CD53, CD72, CD74, CD75, CD77, CD79a, CD79b, CD80, CD81, CD82, CD83, CD84, CD85, and CD86 leukocyte surface markers. These markers have been generally suggested as therapeutic targets for the treatment of B cell disorders or diseases such as B cell malignancies, autoimmune diseases, and transplant rejection. Antibodies that specifically bind them have been developed, and some have been tested as therapeutic agent for the treatment of diseases and disorders.
For example, chimeric or radiolabeled monoclonal antibody (mAb)-based therapies directed against the CD20 cell surface molecule specific for mature B cells and their malignant counterparts have been shown to be an effective in vivo treatment for non-Hodgkin's lymphoma (Tedder et al., Immunol. Today 15:450-454 (1994); Press et al., Hematology: 221-240 (2001); Kaminski et al., N. Engl. J. Med. 329:459-465 (1993); Weiner, Semin. Oncol. 26:43-51 (1999); Onrust et al., Drugs 58:79-88 (1999); McLaughlin et al., Oncology 12:1763-1769 (1998); Reff et al., Blood 83:435-445 (1994); Maloney et al., Blood 90:2188-2195 (1997); Malone et al., J. Clin. Oncol. 15:3266-3274 (1997); Anderson et al., Biochem. Soc. Transac. 25:705-708 (1997)). Anti-CD20 monoclonal antibody therapy has also been found to be partially effective in attenuating the manifestations of rheumatoid arthritis, systemic lupus erythematosus, idiopathic thrombocytopenic purpura and hemolytic anemia, as well as other immune-mediated diseases (Silverman et al., Arthritis Rheum. 48:1484-1492 (2002); Edwards et al., Rheumatology 40:1-7 (2001); De Vita et al., Arthritis Rheumatism 46:2029-2033 (2002); Leandro et al., Ann. Rheum. Dis. 61:883-888 (2002); Leandro et al., Arthritis Rheum. 46:2673-2677 (2001)). The anti-CD20 (IgG1) antibody, RITUXAN™ (rituximab), has successfully been used in the treatment of certain diseases such as adult immune thrombocytopcnic purpura, rheumatoid arthritis, and autoimmune hemolytic anemia (Cured et al., WO 00/67796). Despite the effectiveness of these therapies, B cell depletion is less effective where B cells do not express or express CD20 at low levels, (e.g., on pre-B cells or immature B cells) or have lost CD20 expression following CD20 immunotherapy (Smith et al., Oncogene 22:7359-7368 (2003)).
Murine monoclonal anti-CD19 antibodies have been described in the art, for example, HD37 (IgG1, kappa) (DAKO North America, Inc, Carpinteria, Calif.), BU12 (Callard et al., J. Immunology, 148(10):2983-7 (1992)), 4G7 (IgG1) (Meeker et al., Hybridoma, 3(4):305-20 (1984 Winter)), J4.119 (Beckman Coulter, Krefeld, Germany), B43 (PharMingen, San Diego, Calif.), SJ25C1 (BD PharMingen, San Diego, Calif.), FMC63 (IgG2a) (Zola et al., Immunol. Cell. Biol. 69(PT6): 411-22 (1991); Nicholson et al., Mol. Immunol., 34:1157-1165 (1997); Pietersz et al., Cancer Immunol. Immunotherapy, 41:53-60 (1995)), 89B(B4) (IgG1) (Beckman Coulter, Miami, Fla.; Nadler et al., J. Immunol., 131:244-250 (1983)), and/or HD237 (IgG2b) (Fourth International Workshop on Human Leukocyte Differentiation Antigens, Vienna, Austria, 1989; and Pezzutto et al., J. Immunol., 138(9):2793-2799 (1987)). Anti-CD19 antibodies or conjugates thereof have also shown therapeutic potential in various animal models of B cell disorders and diseases (Falvell et al., Br. J. Hematol. 134(2):157-70 (2006); Vallera et al., Clin. Cancer Res. 11(21):7920-8 (2005); Yazawa et al., Proc. Natl. Acad. Sci. USA 102(42):15178-83 (2005)).
In particular, the use of humanized CD19 antibodies has been described for the treatment of B-cell disease such as lymphoma, leukemia, or autoimmune disease (see, Hansen U.S. Patent Application Publication No. US2005/0070693; U.S. Pat. No. 7,109,304).
Despite recent advances in cancer therapy, B cell malignancies, such as the B cell subtypes of non-Hodgkin's lymphomas, and chronic lymphocytic leukemia, are major contributors of cancer-related deaths. Accordingly, there is a great need for further, improved therapeutic regimens for the treatment of B cell malignancies.
Both cellular (T cell-mediated) and humoral (antibody, B cell-mediated) immunity are now known to play significant roles in graft rejection. While the importance of T cell-mediated immunity in graft rejection is well established, the critical role of humoral immunity in acute and chronic rejection has only recently become evident. Consequently, most of the advances in the treatment and prevention of graft rejection have developed from therapeutic agents that target T cell activation. The first therapeutic monoclonal antibody that was FDA approved for the treatment of graft rejection was the murine monoclonal antibody ORTHOCLONE-OKT3™ (muromonab-CD3), directed against the CD3 receptor of T cells. OKT3 has been joined by a number of other anti-lymphocyte directed antibodies, including the monoclonal anti-CD52 CAMPATH™ antibodies, CAMPATH™-1G, CAMPATH™-1H (alemtuzumab), and CAMPATH™-1M), and polyclonal anti-thymocyte antibody preparations (referred to as anti-thymocyte globulin, or “ATG,” also called “thymoglobin” or “thymoglobulin”). Other T cell antibodies approved for the prevention of transplant rejection include the chimeric monoclonal antibody SIMULECT™ (basiliximab) and the humanized monoclonal antibody ZENAPAX™ (daclizumab), both of which target the high-affinity IL-2 receptor of activated T cells.
The importance of humoral immunity in graft rejection was initially thought to be limited to hyperacute rejection, in which the graft recipient possesses anti-donor HLA antibodies prior to transplantation, resulting in rapid destruction of the graft in the absence of an effective therapeutic regimen of antibody suppression. Recently, it has become evident that humoral immunity is also an important factor mediating both acute and chronic rejection. For example, clinical observations demonstrated that graft survival in patients capable of developing class I or class II anti-HLA alloantibodies (also referred to as “anti-MHC alloantibodies”) was reduced compared to graft survival in patients that could not develop such antibodies. Clinical and experimental data also indicate that other donor-specific alloantibodies and autoantibodies are critical mediators of rejection. For a current review of the evidence supporting a role for donor-specific antibodies in allograft rejection, see Rifle et al., Transplantation, 79:S14-S18 (2005). Thus, due to the relatively recent appreciation of the role of humoral immunity in acute and chronic graft rejection, current therapeutic agents and strategies for targeting humoral immunity are less well developed than those for targeting cellular immunity. Accordingly, there is a need in the art for improved reagents and methods for treating and preventing graft rejection, i.e. graft-versus-host disease (GVHD), humoral rejection, and post-transplantation lymphoproliferative disorder in human transplant recipients.
Autoimmune diseases as a whole cause significant morbidity and disability. Based on incidence data collected from 1965 to 1995, it has been estimated that approximately 1.2 million persons will develop a new autoimmune disease over the next five years. Jacobsen et al. (Clin Immunol. Immunopathol. 84:223 (1997)) evaluated over 130 published studies and estimated that in 1996, 8.5 million people in the United States (3.2% of the population) had at least one of the 24 autoimmune diseases examined in these studies. Considering the major impact of autoimmune diseases on public health, effective and safe treatments are needed to address the burden of these disorders. Thus, there is a need in the art for improved reagents and methods for treating autoimmune disease.